News

“iTunes and the Technology Beyond MP3”

By Dennis Lloyd ● Tuesday, July 1, 2003

Phillip D. Long, senior strategist for the Academic Computing Enterprise at MIT writes about the iTunes Music Store and gives a beginner’s lesson on audio formats titled “Audio File Formats 101.” Also included is a list of websites for further reading about AAC, MP3, MPEG-2 and MPEG-4.

“Overall it looks like AAC is simply a better approach to digital sound encoding. MPEG formal listening tests have demonstrated that for 2 channel sound, that is, typical stereophonic listening, MPEG-2 AAC is able to provide slightly better audio quality at 96Kbps than MP3 at 128Kbps.”

Comments

1

“MPEG-2 AAC is able to provide slightly better audio quality at 96Kbps than MP3 at 128Kbps.”

I encode at 192 now or—alt-preset standard

these findings still do not make a believer than AAC is any better than mp3. WMA makes the exact same claim stating that it has better sound quality and lower compression rates. Still it was a good read, but i dont dig AAC.

Posted by Stasyna on July 1, 2003 at 9:25 AM (CDT)

2

It’s not a bad article, but the technical bits are confused. For example:

You don’t actually “play” the MP3 file itself. To listen to it, you need an MP3 player with a decoder to translate the MP3 file back into a native audio format, in this case AIFF…

is blatantly wrong. (Even from a technical point of view, although MP3 has to be decoded to be played back, players don’t write it out as a file of any format, AIFF or otherwise.) Also:

they take the digitally sampled audio from a CD that is recorded at 44.1KHz (the so-called sampling rate) with a bit depth of 16 bits and throw out quanta (sound samples)...

If ‘quanta’ meant anything wrt sampled sound, they would be the differences between consecutive sample values, not samples themselves. And in any case, audio compression doesn’t throw away samples unless you’re using a very low bitrate, and even then downsampling is usually a much more complex process than simply discarding samples…

However, the gist is generally good: AAC is a technically better format than MP3, and we are likely to see more of it. Exactly how much better is of course open to debate…

For example, I can’t tell the difference between 192kbps MP3 and 128kbps AAC, so I’m happy to re-rip/re-encode, to save space. Others may have different experiences: we all have different ears, and different audio kit, and maybe different encoders and decoders, and different music—all of which will affect the results. So with such subjective matters, it seems just as silly to claim that all 96kbps AACs are better than all 128kbps MP3s as it does to claim that none are.

To judge from the many different claims I’ve seen, I suspect that on average 128kbps AAC is just a little worse than 192kbps MP3 (using a good encoder like lame), though much better than 128kbps MP3. But listen for yourself, and use whatever meets your own criteria.

Posted by Gidds in UK on July 1, 2003 at 9:59 AM (CDT)

3

Good points andrew.
I could clearly hear a difference over my stereo setup, output from computer.

4

Article states that AAc is about 1.3, 1.4 times smaller at equal quality.

That is 256 / 1.35 = 186 about 196kbps AAC. That is what I will wait for from Apple (or anyone else). Give me 256kbps Mp3 or 196kbps AAC. NOW!

Posted by pbox on July 1, 2003 at 3:46 PM (CDT)

5

For 50 year old ears, I personally could not hear a difference between MP3 and ACC when I experimented with encoding the same tune at all the possible encoding rates using iTunes.

So for me, I’ll stick with MP3 since they are more widely compatible with what my friends use.

I would suggest that instead of reading articles written by “experts,” you try various encodings yourself and see what you think.

I assume 12 year olds can hear a difference that those of us who are older have lost the ability to hear.

Posted by Charles on July 1, 2003 at 7:39 PM (CDT)

6

I did blinded testing and 160 kbps AACs sounded as good as -alt present standard EAC/LAME MP3s, which are 200-250 kbps.

I switched to AAC just for the space savings.

The testing was done with headphones and car audio. At home I use either the original WAV or AIFF or Monkey’s audio (lossless compression).

Cheers,

Posted by Alric on July 2, 2003 at 9:59 AM (CDT)

7

For 0.99 cent at least I want a WAV file, not a compressed one, be it MP3 or AAC or whatever!

I use my home stereo (AudioAlchemy DAC, Primare amplifier, custom-made speakers w/ ScanSpeak tweetwrs and Seas Woofers) and I can easily hear the difference between an original CD and a burned one or the difference between an uncompressed music file and compressed music.

0.99$ per song could may be reasonable for full quality. Also consider that the audio standard of the future should be the 96k DVD-Audio with a resolution much higher than the CD.

So… what’s the future of music market? Higher quality at an unreasonable price (even for people like me that invested a lot in hi-fi system) or cheaper low quality compressed music?

COnsider the evolution of the music market in the last 20 years. When I was a teenager (about 15 years ago) an LP was quite cheap but the hardware (turntable, amplifier, speakers) was quite expensive. When companies like Sony - originally an hardware producer - got into the business of software (CD’s) they reasoned: let’s reduce the price of our CD players or DVD players (DVD is extremely young as format and you can find a player for less than 100$) so once people got one they will spend their money on the discs, whose price has been triplicated compared to the old LP’s.

What did Apple do? Simply go back to the origin: they noticed that software (MP3) is now available at a little price (basically for free) so they gave those consumers a high-quality pricey hardware to play it!

Personally, I bought an Ipod a couple of week ago, I like it, I like the design (the original, of course) but still I would prefer higher quality music at a reasonable price. My reasoning is simple: if CD costed half price I would buy MORE than double, and Music industry would than have higher revenues in the long term… but they just rise the price and reduce the catalogue… music as a form of art has hard times… meanwhile I’ll just listen to my 70’s favorites on my Ipod, there’s not much to miss out there at the moment!

Regards.

Posted by Dino on July 2, 2003 at 11:39 PM (CDT)

8

Problem with iPod is you are locked in by Apple. All other players have more support for more formats—I like new Rio Karma that supports FLAC (lossless) and OGG (best lossy compression around).